The present invention relates to a watertight brushless fan motor and a manufacturing method thereof.
Generally, brushless fan motors include a stator provided with a plurality of stator magnetic poles, a circuit substrate fixed to the stator, a rotor for rotating with respect to the stator, and a case. The case includes a bearing supporting cylindrical section in which a bearing for rotatably supporting the rotary shaft of the rotor is received, a cylindrical housing section for surrounding the outer periphery of the rotor, a plate-like section separated from the circuit substrate with a predetermined space and extending from the end of the bearing supporting cylindrical section in a direction perpendicular to the center line of the bearing supporting cylindrical section, and a plurality of webs for connecting the plate-like section to the housing section. In the brushless fan motor of this type, it is required that the stator and the circuit substrate be made watertight. Then, as disclosed in Japanese Patent Application Laid-Open Publication No. 191611/1998, a watertight brushless fan motor has been proposed in which spaces between the plate-like section and the bearing supporting cylindrical section of the case are formed with an insulating resin in such a manner that the stator and the circuit substrate are included inside, thereby forming a molded part.
However, in this conventional watertight brushless fan motor, when the insulating resin is molded, the insulating resin shrinks due to what is called a molding shrinkage or molding sink, or expands or shrinks due to a change in ambient temperature, thereby causing a crack in the outer surface of the molded part.
It is therefore an object of the present invention is to provide a watertight brushless fan motor which can prevent occurrence of a crack in the outer surface of a molded part caused by shrinkage of an insulating resin resulting from the molding shrinkage, or expansion and shrinkage of the insulating resin due to a change in ambient temperature, and a manufacturing method of the watertight brushless fan motor.
It is another object of the present invention to provide a watertight brushless fan motor in which an insulating resin can be molded, with the center line of the cylindrical body of the die of a resin mold aligned over the center line of the bearing supporting cylindrical section of the case, and a manufacturing method of the watertight brushless fan motor.